The present invention relates to a system for recording and reproducing data, and more particularly to a data recording/reproducing system, data storage device, and file access method suitable for recording and reproducing audio, video, and other data.
For example, Patent Reference 1 (refer to Japanese Patent Laid-open No. 2001-14110, page 12, FIG. 1) discloses an audio/video data recording and reproducing system having a low-speed optical disk drive and a high-speed hard-disk drive. In this system, entire data of an audio/video file and only a starting section of the data of the audio/video file are recorded beforehand in the optical disk drive and the hard-disk drive, respectively. When the file is reproduced, the reproduction is started using the starting section stored within the hard-disk drive and at the same time, data that follows the starting section is transferred from the optical disk drive to, and recorded in, the hard-disk drive. Thus, the entire file is continuously reproduced from the hard-disk drive. According to the configuration of this system, reproduction of audio/video data from the optical disk drive slow in storage medium loading, startup, and the like, can be conducted rapidly.
The concept of this system for recording and reproducing digitized audio/video data is described below using FIG. 2. Numeral 1 denotes a data recording/reproducing system, 2 a tuner for receiving TV broadcast data, 3 an antenna, 7 an MPEG decoder for decompressing compressed audio/video data, and 8 an on-screen display controller for displaying channel information, volume information, and the like, in a superimposed condition on an output of the MPEG decoder 7. Numeral 9 denotes a display, 6 a hard-disk drive, 5 a data recording/reproducing controller for recording data in and reproducing it from the hard-disk drive 6, and 4 a stream controller for controlling the flow of audio/video data, the conversion of a format, and the like. Numeral 11 denotes a CPU for controlling the operation of this entire data recording/reproducing system, 12 a ROM within which programs of the CPU 11 are prestored, and 13 a RAM that is used when the programs are executed.
When a TV broadcast is viewed in real time, output data from the tuner 2 is sent to the MPEG decoder 7 via the stream controller 4, then decompressed by the MPEG decoder 7, and displayed on the display 9 via the on-screen display controller 8. In addition, when a TV broadcast is recorded, output data from the tuner 2 is sent to the recording/reproducing controller 5 via the stream controller 4 and then recorded in the hard-disk drive 6. Furthermore, when recorded broadcast data is viewed, the recording/reproducing controller 5 reads out desired data from the hard-disk drive 6 and delivers the data to the stream controller 4, which then displays the data on the display 9 via the MPEG decoder 7 and the on-screen controller 8.
By recording/reproducing compressed audio/video data using the random-accessible hard-disk drive 6, excellent characteristics in terms of operational convenience, such as the ability to read out desired data rapidly from a large volume of stored data, can be supplied in comparison with a recording/reproducing system that uses a recording tape.
FIG. 3 is a diagram showing the concept of the recording format used when the above-mentioned audio/video data is recorded in an internal hard disk 600 of the hard-disk drive 6. Storage area of the hard disk 600 is composed of a volume management area 320, a file management area 330, and a data storage area 340. In the file management area 330 is stored a file name 331 of a file, attributes 332 that denote a size of the file, access control with respect to the file, and other factors, and a block number 333 denoting a location at which a data entity of the file is recorded. The block here refers to a unit of handling an “s” number of sectors each of which is a minimum segment unit on the hard disk 600, and an “s” number of blocks in succession are allocated to one block. During operation, the aforementioned recording/reproducing controller 5 first accesses the volume management area 320 prestored in a zone which starts from a starting sector of the hard-disk drive 6. Next after acquiring a starting block number of the file management area 330, the recording/reproducing controller 5 converts the block number into a sector number, then reads out the file management area 330, and acquires the block number 333 under which data of the desired file is prestored. After this, the recording/reproducing controller 5 calculates the sector number from the block number and specifies the sector number so as to read out data 341.